Machine for spotting a chromatographic element

ABSTRACT

A machine for spotting a chromatographic element has a base containing a reservoir with an upstanding wick. A chromatographic element holding frame is mounted at one end to pivot on the frame and extend over the frame to engage a variable rotary cam driven by a motor on the base. A chromatographic element on the frame repeatedly contacts the upper ends of the wick as the frame rocks. Spots made by the wick may be subjected to a blast of drying air.

United States Patent l 13,568,634

[72] Inventor Carl B. Mankinen [56] References Cited 803 Linden Lane, Davis, Calif. 95616 UNITED STATES PATENTS g5; gg i i 2,536,541 1/1951 11101: 1l8/238X [45] Patented Mar. 9 1971 Primary Examiner-John P. McIntosh [54] MACHINE FOR SPOTTING A CHROMATOGRAPHIC ELEMENT Attorney-L0throp & West ABSTRACT: A machine for spotting a chromatographic element has a base containing a reservoir with an upstanding 9 Claims 3 Drawing Figs wick. A chromatographic element holding frame is mounted [52] U.S. Cl. 118/58, at one end to pivot on the frame and extend over the frame to l l8/238, 1 18/264 engage a variable rotary cam driven by a motor on the base. A [51] Int. Cl B05c l/00 chromatographic element on the frame repeatedly contacts [50] Field of Search 118/238, the upper ends of the wick as the frame rocks, Spots made by 5 8, 264 the wick may be subjected to a blast of drying air.

52 7 a2 1 11 36 1' H 1? /6 5/ L 1 N 4535' j win-1! [film a 5? 7 A r" g I /7 5 1 1 52 11! L41! 7 MAQHENE lFQR SPOTTING A tIllllltQMATOGRAllllC ELEMENT in the conduct of chromatographic analysis, with coated plates, paper sheets and the like, it is a laborious chore to deposit discrete spots of liquid onto the carrier. It is necessary despite repeated contacts to make the spots as evenly spaced and as uniform as possible and this requires tedious handwork and a certain finesse and precision.

Obviously, the customary arrangement for hand operation is subject to extensive improvement, and it is therefore an object of my invention to provide a machine for producing uniform, repeated spots for chromatographic purposes and to do so in a uniform, effective and superior fashion.

Another object of the invention is to provide a machine for spotting chromatographic elements in which various different kinds of elements, such as coated plates or paper sheets, can be readily accommodated.

A further object of the invention is to provide such a machine which is effective to afford a large number of discretely spaced spots across the plate or sheetand in which the spots in different areas can be of different'samples.

Another object of the invention is to provide a machine which can be power driven, yet is extremely simple and reliable in its construction.

A further object of the invention is to provide a'machine in which the drying of the sample spots can be accelerated.

A further object of the invention is to provide a machine of the sort described in which the timing of the spot deposition can be varied.

A further object of the invention is in general to provide an improved machine for spotting chromatographic elements.

Other objects together with the foregoing-are attained in the embodiment of the invention described in the accompanying description and illustrated in the accompanying drawing, in which:

FlG. l is a plan of the spotting device;

l lG. 2 is a cross section, the plane of which is indicated by the line 2-2 of H6. 1; and

Flfi. 3 is a plan of the device with the top frame removed.

While the spotting device can be embodied in a large number of different ways depending upon the desired capacity, the general environment of use and other factors, it has with considerable success been embodied in the form shown herein which has proved useful in laboratory work. The machine is almost entirely fabricated of plastic materials in order to be nonreactive or inert so far as contacting materials are concerned.

ireferably, the machine includes a base 6 made up of a generally rectangular bottom plate 7 on which upstanding sidewalls ti and 9 are provided as well as a rear wall if and spaced apart front walls 12, 13 and l l. All of these walls terminate in a transverse plane substantially parallel to the rectangular plate 7 and are located to leave a platform 16 adjacent one end thereof.

Designed to fit between the walls 12 and 13 and to rest on a floor 117 is a removablereservoir block 18. This can be a single block which extends transversely for the full width of the machine, or can include a number of individually removable sections. in any event, the block 1% preferably includes a number of generally T-shaped reservoir openings 21 extending from the closed bottom 22 of the reservoir to the open top thereof.

Each of the reservoirs 21 is substantially like the others and is effective to receive an upstanding, rectangular wick 23. The wick is preferably of a material which is nonreactive with the sample to be employed and which is fine enough to act as a filter. The wick can conveniently be made of a good grade of felt or of chromatographic paper, properly compacted, and may even include an ion exchange resin or a buffering compound to make qualitative separation in the wick or to keep the solute for the materials to be handled at a desired pH. The wick can be of any desired configuration but preferably is rectangular as shown to slide easily into and out of the reservoir while leaving space for additional liquid and preferably has a narrow or chisel upper edge 24 The wicks are usually positioned in the various reservoirs and then a supply of the liquid sample is added thereto. If desired, all of the reservoirs across the device can be supplied with the same materials, or different reservoirs can have different materials therein since the reservoirs are not in communication.

Preferably, the wicks all extend upwardly above the reservoirs to substantially the same plane, although since the wicks are somewhat flexible they can deflect slightly in the event they happen to be of uneven height.

Mounted on the base 6 at the end opposite the platform 16 are upstanding pivot members 26 and 27 aligned transversely of the device and just above the upper edge of the surrounding wall. Designed to rest on the pivots at one end is a frame 3t made up of walls 32 arranged in rectangular form and spanned across one end by a plate 33 which itself bears on the pivots 26 and 27 and spanned across the other end by a plate 34 which adds stiffness and reinforcement.

The plate 34 likewise carries a cam follower 36 designed to rest on a variable rotary cam 37 included in a means for rais ing and lowering the frame 31. The cam 37 is comprised of a pair of relatively rotatable discs 38 and 39 of irregular peripheral contour, both being fastened on a shaft 41 by a releasable nut 42. The shaft 451 projects from an electrically driven motor 43 mounted on the platform 16.

The diameter of the cam discs'is such that when the frame 32 is lowered with the follower 36 resting on a high zone of the cam discs, the frame is substantially above and spaced away from the upper ends of the wicks, but when the cams revolve, the follower 36 periodically drops into the gaps in the cam periphery resulting from rotary displacement of the two cam discs. The gap can be made of substantially any extent desired by loosening the nut 42 and rotating the discs 38 and 49 relative to each other. Following that, when the nut is tightened, the cam will repeatedly oscillate the follower 36 in accordance with the contact duration provided by the gaps in the overlapped portions of the cam lobes.

in the use of the structure a sheet to receive the chromatographic sample is mounted on the cross plates 33 and 34. This sheet can be a sheet of paper or a glass plate, for example, having a coated nether surface which sheet or plate fits between the walls 32 and is adequately supported thereby in a confined location. When the wicks have become moist the motor 43 is energized and then lifts and lowers the frame 32. ln lowered position the plate or sheet contacts all of the upwardly extending wicks and receives spots therefrom. The motor may raise and lower a sheet or plate a number of times; for example, 50 times, in affording an appropriate deposit from each wick. in a representative case there are 15 spots made crosswise or transversely of the plate or sheet.

Despite the large number of contacts between the wicks and the plate or sheet, it has been found that since the wicks are slightly yieldable and are not abrasive, the deposit of liquid on the substratum occurs uniformly and without deleterious friction or abrasion. The spots are all uniformly made since the 15th repetition is the same as the first and the contact duration is governed by the machine. Hence, a great deal of tedious hand labor is obviated and uniform, superior results are attained by machine use.

in many instances it is desired that the spots dry somewhat faster than they would by ordinary ambient air circulation. F or that reason, between the walls l3 and 14 I provide a number of upstanding air ducts 51, all of which connect to a transverse air manifold 52 supplied with air under pressure through a flexible hose 53. Thus, as and after the spots are made on the superposed plate or sheet, air traverses the area and facilitates prompt evaporation so that successive spots remain about the same size and do not enlarge.

In general, the machine for spotting chromatographic elements in accordance with this description has been successfully employed in obviating tedious hand labor and in providing uniform and representative chromatographic samples.

in other instances it may be desired to provide transverse streaks rather than spots; that is, a single contact having the same transverse extent as several spots. For example, three transverse streaks can be provided in the device shown in FIG. 3 by interconnecting all of the openings 21 in each of the blocks 18 and providing one wick in each of the blocks extending for its full width. In that event, the wide wick is preferably covered and supported on its leading and trailing faces, at least by upright glass plates also fitting into the openings and extending nearly to the wick top. The plates help to hold the wick in position and also inhibit evaporation from the covered surfaces.

lclaim:

1. A machine for spotting a chromatographic element comprising a base, a liquid reservoir on said base, a wick in said reservoir and extending thereabove, a frame, means for supporting said frame adjacent one end thereof on said base, means on said base and engaging said frame adjacent the other end thereof for repeatedly raising and lowering said frame, and means on said frame for holding a chromatographic element in position to abut the upper ends of said wick.

2. A machine as in claim 1 in which said raising and lowering means includes a follower on said frame and a cam engaging said follower.

3. A machine as in claim 2 in which said cam has a variable cam contour.

4. A machine as in claim 2 in which said cam is rotatable.

5. A machine as in claim 1 in which said reservoir is removable from said base.

6. A machine as in claim 1 in which said supporting means includes a pivot.

7. A machine as in claim 1 in which said base is substantially rectangular in plan, a plurality of said reservoirs extend transversely of said base adjacent one end thereof, said frame is substantially rectangular, said supporting means includes pivot devices disposed adjacent the other end of said base and engaging the nether portion of said frame, and said raising and lowering mechanism includes a motor driven cam at said one end of said base and a follower on said end of said frame engaging the upper portion of said cam.

8. A machine as in claim 1 including means for directing air upwardly adjacent said wick.

9. A machine as in claim 8 in which said directing means includes a duct in said base alongside said reservoir. 

1. A machine for spotting a chromatographic element comprising a base, a liquid reservoir on said base, a wick in said reservoir and extending thereabove, a frame, means for supporting said frame adjacent one end thereof on said base, means on said base and engaging said frame adjacent the other end thereof for repeatedly raising and lowering said frame, and means on said frame for holding a chromatographic element in position to abut the upper ends of said wick.
 2. A machine as in claim 1 in which said raising and lowering means includes a follower on said frame and a cam engaging said follower.
 3. A machine as in claim 2 in which said cam has a variable cam contour.
 4. A machine as in claim 2 in which said cam is rotatable.
 5. A machine as in claim 1 in which said reservoir is removable from said base.
 6. A machine as in claim 1 in which said supporting means includes a pivot.
 7. A machine as in claim 1 in which said base is substantially rectangular in plan, a plurality of said reservoirs extend transversely of said base adjacent one end thereof, said frame is substantially rectangular, said supporting means includes pivot devices disposed adjacent the other end of said base and engaging the nether portion of said frame, and said raising and lowering mechanism includes a motor driven cam at said one end of said base and a follower on said end of said frame engaging the upper portion of said cam.
 8. A machine as in claim 1 including means for directing air upwardly adjacent said wick.
 9. A machine as in claim 8 in which said directing means includes a duct in said base alongside said reservoir. 